Increasing dynamically SGA_TARGET hang sqlplus session on RHEL 5.4

Dear All,

We have E-Business Suite 12.1.1 installed on RHEL 5.4 kernel (2.6.18-164.11.1.el5).

Our Production Database version 11.1.0.7.0 is set SGA_MAX_SIZE=6G and SGA_TARGET=4G.

While increasing dynamically the SGA_TARGET=4250m the sqlplus session is hanging. It is not doing anything for hours. Finally we are breaking it with Ctrl+C and we received the message as below.

SQL> alter system set sga_target=4563402752 scope=both;
alter system set sga_target=4563402752 scope=both
*
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-01013: user requested cancel of current operation

Below is my kernel parameters for the both TEST and PROD having 16G physicall memory.